The present invention concerns an information recording medium of the type having a first coat, which can be discolored in certain areas corresponding to the area-limited action of heat. The invention also concerns a non-mechanical recording method for making a record on such a recording medium.
In known non-mechanical electronic recording methods, a thin metal coat is burned away in a limited area on a dark paper by means of a well-contacting pin electrode, due to the passage of current. With a buildup time of the arc of about 0.5 .mu.s and a burning time of about 10 .mu.s, very high recording powers of up to about 100 kHz are obtained. The relatively long burning times required to obtain high optical contrast conditions disadvantageously leads to a relatively great consumption of the writing electrode. Therefore, in order to obtain a longer service life, self-adjusting electrodes are used. The use of self-adjusting electrodes typically limits the three-dimensional resolution in a multi-electrode arrangement for reasons of mechanical stability to about 2.5 lines per millimeter.
In another single-stage method, the so-called "thermo-reactive method", paper is impregnated with the colorless mixture of two chemical compounds, for example, (a) triphenylmethane-naphthalide and (b) biphenol A. A resistance-heated, well-contacting pin electrode generates local temperature fiels equal to or greater than 300.degree. C. At this temperature, a thermal reaction takes place between the two components, (a) and (b), so that, in the forementioned example, a deep blue compound (c) is obtained. Typical heating times for a temperature of 380.degree. C. are about 5 .mu.s with thermal pressure heads in thin-film technique, the local resolution is about five lines per millimeter.
A disadvantage of this high degree of heat application is that the temperature rises slowly, so that an increasingly stronger annoying background coloration is obtained. In addition, the method is too slow.